What's causing hearing loss for millions of Americans?

Millions of U.S. adults have some sort of hearing damage and a surprising number don’t even know it, according to a new report from the Centers for Disease Control and Prevention.

Hearing loss affects around 40 million adults — one in five between the ages of 20 and 69. It is the third most common chronic condition in the U.S. Almost twice as many people report hearing loss as report diabetes or cancer.

While lengthy exposure to loud sounds at a noisy workplace is a common culprit, the new report emphasizes that the routine noise of everyday modern life can damage hearing just as much.

“Forty million Americans show some hearing damage from loud noise, with nearly 21 million reporting no exposure to loud noise at work,” CDC Acting Director Dr. Anne Schuchat said in a statement. “This can be distressing for people affected and their loved ones.”

“What’s causing it is loud noise and it’s not just how loud the noise is, it’s how long someone’s exposed to it,” CBS News medical contributor Dr. David Agus told “CBS This Morning.” “A moderate noise for a long period of time can cause hearing loss.”